<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>验证码邮件</title>
    <style>
        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            line-height: 1.6;
            color: #333;
            max-width: 500px;
            margin: 0 auto;
            padding: 20px;
            background-color: #f8f9fa;
        }
        .container {
            background-color: #ffffff;
            padding: 40px;
            border-radius: 12px;
            box-shadow: 0 4px 25px rgba(0,0,0,0.1);
            text-align: center;
        }
        .header {
            margin-bottom: 30px;
        }
        .header h1 {
            color: #28a745;
            margin: 0;
            font-size: 24px;
            font-weight: 600;
        }
        .verification-code {
            background: linear-gradient(135deg, #28a745, #20c997);
            color: white;
            font-size: 32px;
            font-weight: bold;
            padding: 20px 30px;
            border-radius: 8px;
            margin: 25px 0;
            letter-spacing: 8px;
            display: inline-block;
            box-shadow: 0 4px 15px rgba(40, 167, 69, 0.3);
        }
        .info {
            background-color: #fff3cd;
            border: 1px solid #ffeaa7;
            color: #856404;
            padding: 15px;
            border-radius: 6px;
            margin: 20px 0;
        }
        .warning {
            background-color: #f8d7da;
            border: 1px solid #f5c6cb;
            color: #721c24;
            padding: 15px;
            border-radius: 6px;
            margin: 20px 0;
        }
        .footer {
            margin-top: 30px;
            padding-top: 20px;
            border-top: 1px solid #eee;
            color: #666;
            font-size: 14px;
        }
        .expire-time {
            color: #dc3545;
            font-weight: bold;
        }
    </style>
</head>
<body>
    <div class="container">
        <div class="header">
            <h1>🔐 验证码</h1>
        </div>
        
        <p>您好，${username}！</p>
        
        <p>您正在进行 <strong>${operation}</strong> 操作，请使用以下验证码：</p>
        
        <div class="verification-code">
            ${verificationCode}
        </div>
        
        <div class="info">
            <p><strong>📝 使用说明：</strong></p>
            <p>请在 <span class="expire-time">${expireMinutes} 分钟</span> 内输入此验证码完成验证。</p>
        </div>
        
        <div class="warning">
            <p><strong>⚠️ 安全提醒：</strong></p>
            <p>• 请勿将验证码告诉他人</p>
            <p>• 如非本人操作，请忽略此邮件</p>
            <p>• 验证码仅限本次使用</p>
        </div>
        
        <div class="footer">
            <p>此邮件由系统自动发送，请勿回复。</p>
            <p>发送时间：${sendTime}</p>
            <p>&copy; 2024 EasyMail 邮件服务</p>
        </div>
    </div>
</body>
</html>